Liquid crystal composition and liquid crystal display device

ABSTRACT

A liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of the nematic phase, a small viscosity, a large optical anisotropy, a large negative dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light, a high stability to heat and a short helical pitch is provided, wherein the liquid crystal composition has a negative dielectric anisotropy and contains a specific optically active compound as a first compound, a specific compound having a large negative dielectric anisotropy as a second component, and may contain a specific compound having a high maximum temperature or a small viscosity as a third component, a specific compound having a large negative dielectric anisotropy as a fourth component and a specific optically active compound as a fifth component, and a liquid crystal display device that contains the composition.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 of international application of PCTapplication serial no. PCT/JP2010/064945, filed on Sep. 1, 2010, whichclaims the priority benefit of Japan application no. 2009-227091, filedon Sep. 30, 2009. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

TECHNICAL FIELD

The invention relates to a liquid crystal composition mainly suitablefor use in an active matrix (AM) device and so forth, and an AM deviceand so forth containing the composition. More specifically, theinvention relates to a liquid crystal composition having a negativedielectric anisotropy, and a device that contains the composition andhas a mode such as an in-plane switching (IPS) mode, a verticalalignment (VA) mode or a polymer sustained alignment (PSA) mode.

BACKGROUND ART

In a liquid crystal display device, a classification based on anoperating mode for liquid crystals includes a phase change (PC) mode, atwisted nematic (TN) mode, a super twisted nematic (STN) mode, anelectrically controlled birefringence (ECB) mode, an opticallycompensated bend (OCB) mode, an in-plane switching (IPS) mode, avertical alignment (VA) mode and a polymer sustained alignment (PSA)mode. A classification based on a driving mode in the device includes apassive matrix (PM) and an active matrix (AM). The PM is furtherclassified into static, multiplex and so forth, and the AM is classifiedinto a thin film transistor (TFT), a metal insulator metal (MIM) and soforth. The TFT is further classified into amorphous silicon andpolycrystal silicon. The latter is classified into a high temperaturetype and a low temperature type according to a production process. Aclassification based on a light source includes a reflective typeutilizing natural light, a transmissive type utilizing backlight and atransreflective type utilizing both the natural light and the backlight.

The devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to obtainan AM device having good general characteristics. Table 1 belowsummarizes a relationship between two of the general characteristics.The general characteristics of the composition will be further explainedbased on a commercially available AM device. A temperature range of thenematic phase relates to a temperature range in which the device can beused. A preferred maximum temperature of the nematic phase is about 70°C. or higher and a preferred minimum temperature of the nematic phase isabout −10° C. or lower. Viscosity of the composition relates to aresponse time in the device. A short response time is preferred fordisplaying moving images on the device. Accordingly, a small viscosityin the composition is preferred. A small viscosity at a low temperatureis further preferred.

TABLE 1 General Characteristics of Composition and AM Device GeneralCharacteristics General Characteristics No. of Composition of AM Device1 wide temperature range of wide usable temperature range a nematicphase 2 small viscosity ¹⁾ short response time 3 suitable opticalanisotropy large contrast ratio 4 large positive or negative lowthreshold voltage and small dielectric anisotropy electric powerconsumption large contrast ratio 5 large specific resistance largevoltage holding ratio and large contrast ratio 6 high stability toultraviolet long service life light and heat

An optical anisotropy of the composition relates to a contrast ratio inthe device. A product (Δn×d) of the optical anisotropy (Δn) of thecomposition and a cell gap (d) in the device is designed so as tomaximize the contrast ratio. A suitable value of the product depends ona type of the operating mode. The suitable value is in the range ofabout 0.30 micrometer to about 0.40 micrometer in a device having the VAmode, and in the range of about 0.20 micrometer to about 0.30 micrometerin a device having the IPS mode. In the above case, a composition havinga large optical anisotropy is preferred for a device having a small cellgap. A large absolute value of a dielectric anisotropy in thecomposition contributes to a low threshold voltage, a small electricpower consumption and a large contrast ratio in the device. Accordingly,the large absolute value of the dielectric anisotropy is preferred. Alarge specific resistance in the composition contributes to a largevoltage holding ratio and a large contrast ratio in the device.Accordingly, a composition having a large specific resistance, at roomtemperature and also at a high temperature in an initial stage, ispreferred. A composition having a large specific resistance, at roomtemperature and also at a high temperature after the device has beenused for a long time, is preferred. Stability of the composition toultraviolet light and heat relates to a service life of the liquidcrystal display device. In the case where the stability is high, thedevice has a long service life. Such characteristics are preferred foran AM device used in a liquid crystal projector, a liquid crystaltelevision and so forth.

A composition having a positive dielectric anisotropy is used for an AMdevice having the TN mode. On the other hand, a composition having anegative dielectric anisotropy is used for an AM device having the VAmode. A composition having a positive or negative dielectric anisotropyis used for an AM device having the IPS mode. A composition having apositive or negative dielectric anisotropy is used for an AM devicehaving the PSA mode. Examples of the liquid crystal composition havingthe positive dielectric anisotropy are disclosed in Patent literaturesas described in the following. Examples of the liquid crystalcomposition containing an optically active compound are disclosed inPatent literature No. 3 but a helical pitch has not been sufficientlyshort.

CITATION LIST Patent Literature

-   Patent literature No. 1: JP H2-67232 A.-   Patent literature No. 2: JP H5-229979 A.-   Patent literature No. 3: JP H6-200251 A.

A desirable AM device has characteristics such as a wide temperaturerange in which a device can be used, a short response time, a largecontrast ratio, a low threshold voltage, a large voltage holding ratioand a long service life. A shorter response time even by one millisecondis desirable. Thus, desirable characteristics of a composition include ahigh maximum temperature of a nematic phase, a low minimum temperatureof the nematic phase, a small viscosity, a suitable optical anisotropy,a large positive or negative dielectric anisotropy, a large specificresistance, a high stability to ultraviolet light, a high stability toheat and a short helical pitch.

SUMMARY OF INVENTION Technical Problem

One of the aims of the invention is to provide a liquid crystalcomposition satisfying at least one of characteristics such as a highmaximum temperature of a nematic phase, a low minimum temperature of thenematic phase, a small viscosity, a suitable optical anisotropy, a largenegative dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light, a high stability to heat and a shorthelical pitch. Another aim is to provide a liquid crystal compositionhaving a suitable balance regarding at least two of the characteristics.A further aim is to provide a liquid crystal display device containingsuch a composition. An additional aim is to provide a composition havinga suitable optical anisotropy to be a small optical anisotropy or alarge optical anisotropy, a large negative dielectric anisotropy, a highstability to ultraviolet light, a short helical pitch and so forth, andis to provide an AM device having a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth.

Solution to Problem

The invention concerns a liquid crystal composition that has a negativedielectric anisotropy and contains at least one compound selected fromthe group of compounds represented by formula (1) as a first componentand at least one compound selected from the group of compoundsrepresented by formula (2) as a second component, and concerns a liquidcrystal display device containing the composition:

wherein R¹, R⁴ and R⁵ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; R² and R³ are each differently alkyl having 1 to 12 carbonsor alkenyl having 2 to 12 carbons; ring A and ring B are independently1,4-cyclohexylene or 1,4-phenylene; ring C is independently1,4-cyclohexylene, 1,4-phenylene in which arbitrary hydrogen may bereplaced by fluorine or chlorine, or tetrahydropyran-2,5-diyl; Z¹ isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; X¹and X² are independently fluorine or chlorine; Y¹ is hydrogen or —CH₃;and k is 1, 2 or 3. When combining two or more compounds represented byformula (1) and using the compounds, a compound having an identicaltwist direction is preferably used for shorting a helical pitch of thecomposition and minimizing an adding amount of the compound representedby formula (1). However, the compound having the identical twistdirection and a compound having a reverse twist direction can becombined for adjusting temperature dependency of length of the helicalpitch of the composition.

Advantageous Effects of Invention

An advantage of the invention is a liquid crystal composition satisfyingat least one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of the nematic phase, a smallviscosity, a large optical anisotropy, a large negative dielectricanisotropy, a large specific resistance, a high stability to ultravioletlight, a high stability to heat and a short helical pitch. One aspect ofthe invention is a liquid crystal composition having a suitable balanceregarding at least two of the characteristics. Another aspect is aliquid crystal display device containing such a composition. A furtheraspect is a composition having a large optical anisotropy, a largenegative dielectric anisotropy, a high stability to ultraviolet lightand so forth, and is an AM device having a short response time, a largevoltage holding ratio, a large contrast ratio, a long service life, alow light leakage and so forth.

DESCRIPTION OF EMBODIMENTS

Usage of terms in the specification and claims is as described below. Aliquid crystal composition or a liquid crystal display device of theinvention may be abbreviated as “composition” or “device,” respectively.The liquid crystal display device is a generic term for a liquid crystaldisplay panel and a liquid crystal display module. “Liquid crystalcompound” means a compound having a liquid crystal phase such as anematic phase or a smectic phase, or a compound having no liquid crystalphase but being useful as a component of the composition. Such a usefulcompound has a six-membered ring such as 1,4-cyclohexylene and1,4-phenylene, and a rod-like molecular structure. An optically activecompound other than a first component and a polymerizable compound mayoccasionally be added to the composition. Even in the case where thecompound is liquid crystalline, the compound is classified as anadditive herein. At least one compound selected from the group ofcompounds represented by formula (1) may be abbreviated as “compound(1).” “Compound (1)” means one compound or two or more compoundsrepresented by formula (1). A same rule applies to any other compoundrepresented by any other formula. “Arbitrary” means any of not onlypositions but also numbers without including the case where the numberis 0 (zero).

A higher limit of a temperature range of the nematic phase may beabbreviated as “maximum temperature.” A lower limit of the temperaturerange of the nematic phase may be abbreviated as “minimum temperature.”An expression “a specific resistance is large” means that thecomposition has a large specific resistance at room temperature and alsoat a temperature close to the maximum temperature of the nematic phasein an initial stage, and that the composition has a large specificresistance at room temperature and also at a temperature close to themaximum temperature of the nematic phase even after the device has beenused for a long time. An expression “a voltage holding ratio is large”means that the device has a large voltage holding ratio at roomtemperature and also at a high temperature in an initial stage, and thatthe device has a large voltage holding ratio at room temperature andalso at a temperature close to the maximum temperature of the nematicphase even after the device has been used for a long time. Whencharacteristics such as an optical anisotropy are explained, valuesobtained according to the measuring methods described in Examples willbe used. The first component includes one compound or two or morecompounds. “Ratio of the first component” is expressed in terms of aweight ratio (part by weight) of the first component when the weight ofthe liquid crystal composition excluding the first component and thefifth component is defined to be 100. “Ratio of the second component” isexpressed in terms of weight percent (% by weight) of the secondcomponent based on the weight of the liquid crystal compositionexcluding the first component and the fifth component. “Ratio of thethird component” and “ratio of the fourth component” are expressed in amanner similar to “ratio of the second component.” “Ratio of the fifthcomponent” is expressed in a manner similar to “ratio of the firstcomponent.” A ratio of the additive mixed with the composition isexpressed in terms of weight percent (% by weight) or weight parts permillion (ppm) based on the total weight of the liquid crystalcomposition.

A symbol R¹ is used for a plurality of compounds in chemical formulas ofcomponent compounds. R¹ to be selected may be identical or different intwo of arbitrary compounds among a plurality of the compounds. In onecase, for example, R¹ of compound (1-1) is ethyl and R¹ of compound(1-2) is ethyl. In another case, R¹ of compound (1-1) is ethyl and R¹ ofcompound (1-2) is propyl. A same rule applies to a symbol R⁴, R⁵ or thelike.

The invention includes the items described below.

Item 1. A liquid crystal composition that has a negative dielectricanisotropy and contains at least one optically active compound selectedfrom the group of compounds represented by formula (1) as a firstcomponent and at least one compound selected from the group of compoundsrepresented by formula (2) as a second component:

wherein R¹, R⁴ and R⁵ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; R² and R³ are each differently alkyl having 1 to 12 carbonsor alkenyl having 2 to 12 carbons; ring A and ring B are independently1,4-cyclohexylene or 1,4-phenylene; ring C is independently1,4-cyclohexylene, 1,4-phenylene in which arbitrary hydrogen may bereplaced by fluorine or chlorine, or tetrahydropyran-2,5-diyl; Z¹ isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; X¹and X² are independently fluorine or chlorine; Y¹ is hydrogen or —CH₃;and k is 1, 2 or 3.

Item 2. The liquid crystal composition according to item 1, wherein, informula (1), a sum of carbons of R² and R³ is in the range of 3 to 10.

Item 3. The liquid crystal composition according to item 1, wherein thefirst component is at least one compound selected from the group ofcompounds represented by formula (1-1) to formula (1-3):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine.

Item 4. The liquid crystal composition according to any one of items 1to 3, wherein the second component is at least one compound selectedfrom the group of compounds represented by formula (2-1) to formula(2-15):

wherein R⁴ and R⁵ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

Item 5. The liquid crystal composition according to item 4, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-1).

Item 6. The liquid crystal composition according to item 4, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1) and at least onecompound selected from the group of compounds represented by formula(2-4).

Item 7. The liquid crystal composition according to item 4, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1) and at least onecompound selected from the group of compounds represented by formula(2-7).

Item 8. The liquid crystal composition according to any one of items 1to 7, further containing at least one compound selected from the groupof compounds represented by formula (3) as a third component:

wherein R⁶ and R⁷ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring D and ring E are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z² isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andm is 1, 2 or 3.

Item 9. The liquid crystal composition according to item 8, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1) to formula (3-13):

wherein R⁶ and R⁷ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

Item 10. The liquid crystal composition according to item 9, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1).

Item 11. The liquid crystal composition according to item 9, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-1) and at least onecompound selected from the group of compounds represented by formula(3-5).

Item 12. The liquid crystal composition according to any one of items 1to 11, further containing at least one compound selected from the groupof compounds represented by formula (4) as a fourth component:

wherein R⁸ and R⁹ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring F is independently 1,4-cyclohexylene, 1,4-phenylene inwhich arbitrary hydrogen may be replaced by fluorine or chlorine, ortetrahydropyran-2,5-diyl; Z³ is independently a single bond, ethylene,methyleneoxy or carbonyloxy; and n is 1, 2 or 3.

Item 13. The liquid crystal composition according to item 12, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-1) to formula (4-5):

wherein R⁸ and R⁹ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

Item 14. The liquid crystal composition according to item 13, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-4).

Item 15. The liquid crystal composition according to any one of items 1to 14, further containing a compound represented by formula (5) as afifth component:

Item 16. The liquid crystal composition according to any one of items 1to 15, wherein a ratio of the first component is in the range of 0.01part by weight to 5 parts by weight based on 100 parts by weight of theliquid crystal composition excluding the first component and the fifthcomponent.

Item 17. The liquid crystal composition according to any one of items 1to 16, wherein a ratio of the second component is in the range of 5% byweight to 80% by weight based on the weight of the liquid crystalcomposition excluding the first component and the fifth component.

Item 18. The liquid crystal composition according to any one of items 8to 17, wherein a ratio of the third component is in the range of 5% byweight to 80% by weight based on the weight of the liquid crystalcomposition excluding the first component and the fifth component.

Item 19. The liquid crystal composition according to any one of items 12to 18, wherein a ratio of the fourth component is in the range of 3% byweight to 30% by weight based on the weight of the liquid crystalcomposition excluding the first component and the fifth component.

Item 20. The liquid crystal composition according to any one of items 1to 19, wherein a maximum temperature of a nematic phase is 70° C. orhigher, an optical anisotropy (25° C.) at a wavelength of 589 nanometersis 0.08 or more, and a dielectric anisotropy (25° C.) at a frequency of1 kHz is −2 or less.

Item 21. A liquid crystal display device, containing the liquid crystalcomposition according to any one of items 1 to 20.

Item 22. The liquid crystal display device according to item 21, whereinan operating mode in the liquid crystal display device is a VA mode, anIPS mode or a PSA mode, and a driving mode in the liquid crystal displaydevice is an active matrix mode.

The invention further includes the following items: (1) the composition,further containing the optically active compound; (2) the composition,further containing the additive such as an antioxidant, an ultravioletlight absorber or an antifoaming agent; (3) an AM device containing thecomposition; (4) a device containing the composition, and having a TN,ECB, OCB, IPS, VA or PSA mode; (5) a transmissive device, containing thecomposition; (6) use of the composition as the composition having thenematic phase; and (7) use of the composition as an optically activecomposition.

The composition of the invention will be explained in the followingorder. First, a constitution of the component compounds in thecomposition will be explained. Second, main characteristics of thecomponent compounds and main effects of the compounds on the compositionwill be explained. Third, a combination of components in thecomposition, a preferred ratio of the component compounds and the basisthereof will be explained. Fourth, a preferred embodiment of thecomponent compounds will be explained. Fifth, specific examples of thecomponent compounds will be shown. Sixth, the additive that may be mixedwith the composition will be explained. Seventh, methods forsynthesizing the component compounds will be explained. Last, anapplication of the composition will be explained.

First, the constitution of the component compounds in the compositionwill be explained. The composition of the invention is classified intocomposition A and composition B. Composition A may further contain anyother liquid crystal compound, the additive and an impurity. “Any otherliquid crystal compound” means a liquid crystal compound different fromcompound (1), compound (2), compound (3), compound (4) and compound (5).Such a compound is mixed with the composition for the purpose of furtheradjusting the characteristics. Of any other liquid crystal compounds, aratio of a cyano compound is preferably as small as possible in view ofstability to heat or ultraviolet light. A further preferred ratio of thecyano compound is 0% by weight. The additive includes the opticallyactive compound other than the first component, the antioxidant, theultraviolet light absorber, a coloring matter, the antifoaming agent,the polymerizable compound and a polymerization initiator. The impurityincludes a compound mixed in a process such as preparation of thecomponent compounds. Even in the case where the compound is liquidcrystalline, the compound is classified as the impurity herein.

Composition B consists essentially of compounds selected from the groupof compound (1), compound (2), compound (3), compound (4) and compound(5). A term “essentially” means that the composition may also containthe additive and the impurity, but does not contain any liquid crystalcompound different from the compounds. Composition B has a smallernumber of components than composition A has. Composition B is preferredto composition A in view of cost reduction. Composition A is preferredto composition B in view of possibility of further adjusting physicalproperties by mixing any other liquid crystal compound.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the characteristics of the composition willbe explained. The main characteristics of the component compounds aresummarized in Table 2 on the basis of advantageous effects of theinvention. In Table 2, a symbol L stands for “large” or “high,” a symbolM stands for “medium,” and a symbol S stands for “small” or “low.” Thesymbols L, M and S represent classification based on a qualitativecomparison among the component compounds, and 0 (zero) means “a value isnearly zero.”

TABLE 2 Characteristics of Compounds Compound Compound CompoundCompounds (2) (3) (4) Maximum Temperature S to M S to L S to M ViscosityM S to M M to L Optical Anisotropy M to L M to L M to L DielectricAnisotropy L ¹⁾ 0 L ¹⁾ Specific Resistance L L L ¹⁾ A value of thedielectric anisotropy is negative, and the symbol shows magnitude of anabsolute value.

Upon mixing the component compounds with the composition, the maineffects of the component compounds on the characteristics of thecomposition are as described below. Compound (1) and compound (5)shorten a pitch. Compound (2) decreases the minimum temperature andincreases the absolute value of the dielectric anisotropy. Compound (3)increases the maximum temperature or decreases viscosity. Compound (4)increases the absolute value of the dielectric anisotropy.

Third, the combination of the components in the composition, thepreferred ratio of the components and the basis thereof will beexplained. The combination of the components in the composition includesa combination of the first component and the second component, acombination of the first component, the second component and the thirdcomponent, a combination of the first component, the second componentand the fourth component, a combination of the first component, thesecond component and the fifth component, a combination of the firstcomponent, the second component, the third component and the fourthcomponent, a combination of the first component, the second component,the third component and the fifth component, a combination of the firstcomponent, the second component, the fourth component and the fifthcomponent, and a combination of the first component, the secondcomponent, the third component, the fourth component and the fifthcomponent. A preferred combination of the components in the compositionincludes the combination of the first component, the second component,the third component, the fourth component and the fifth component.

A preferred ratio of the first component is about 0.01 parts by weightor more and about 5 parts by weight or less. A further preferred ratiois in the range of about 0.05 part by weight to about 3 parts by weight.A particularly preferred ratio is in the range of about 0.1 part byweight to about 2 parts by weight.

A preferred ratio of the second component is about 5% by weight or morefor increasing the absolute value of the dielectric anisotropy, andabout 80% by weight or less for decreasing the minimum temperature. Afurther preferred ratio is in the range of about 15% by weight to about65% by weight. A particularly preferred ratio is in the range of about25% by weight to about 60% by weight.

A preferred ratio of the third component is about 5% by weight or morefor increasing the maximum temperature or decreasing the viscosity, andabout 80% or less for increasing the absolute value of the dielectricanisotropy. A further preferred ratio is in the range of about 15% byweight to about 70% by weight. A particularly preferred ratio is in therange of about 25% by weight to about 65% by weight.

A preferred ratio of the fourth component is about 3% by weight or morefor increasing the absolute value of the dielectric anisotropy, andabout 30% by weight or less for decreasing the viscosity. A furtherpreferred ratio is in the range of about 5% by weight to about 20% byweight. A particularly preferred ratio is in the range of about 5% byweight to about 15% by weight.

A preferred ratio of the fifth component is about 0.01 part by weight ormore and about 5 parts by weight or less. A further preferred ratio isin the range of about 0.05 part by weight to about 3 parts by weight. Aparticularly preferred ratio is in the range of about 0.1 part by weightto about 2 parts by weight.

Fourth, the preferred embodiment of the component compounds will beexplained. R¹, R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ are independently alkyl having1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogenis replaced by fluorine. Preferred R¹, R⁴, R⁶, R⁷, R⁸ or R⁹ is alkylhaving 1 to 12 carbons for increasing the stability to ultraviolet lightor heat, or the like. Preferred R⁵ is alkoxy having 1 to 12 carbons forincreasing the absolute value of the dielectric anisotropy. R² and R³are independently alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons. Preferred R² or R³ is alkyl having 1 to 12 carbons forincreasing the stability to ultraviolet light or heat, or the like.

Preferred alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. Further preferred alkyl is ethyl, propyl, butyl, pentyl orheptyl for decreasing the viscosity.

Preferred alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. Further preferred alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Preferred alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. Furtherpreferred alkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl fordecreasing the viscosity. A preferred configuration of —CH═CH— in thealkenyl depends on a position of a double bond. Trans is preferred inthe alkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl and 3-hexenyl for decreasing the viscosity, for instance. Cis preferred in the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl.In the alkenyl, straight-chain alkenyl is preferred to branched-chainalkenyl.

Preferred examples of alkenyl in which arbitrary hydrogen is replaced byfluorine include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. Further preferred examples include2,2-difluorovinyl and 4,4-difluoro-3-butenyl for decreasing theviscosity.

Ring A and ring B are independently 1,4-cyclohexylene or 1,4-phenylene.Preferred ring A or ring B is 1,4-cyclohexylene for decreasing theminimum temperature. Ring C and ring F are independently1,4-cyclohexylene, 1,4-phenylene in which arbitrary hydrogen may bereplaced by fluorine or chlorine, or tetrahydropyran-2,5-diyl. Two ofarbitrary ring C when k is 2 or 3 may be identical or different. Two ofarbitrary ring F when n is 2 or 3 may be identical or different.Preferred ring C or ring F is 1,4-cyclohexylene for increasing themaximum temperature or decreasing the viscosity, and 1,4-phenylene forincreasing the optical anisotropy. Ring D and ring E are independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or3-fluoro-1,4-phenylene. Two of arbitrary ring D when m is 2 or 3 may beidentical or different. Preferred ring D or ring E is 1,4-cyclohexylenefor increasing the maximum temperature or decreasing the viscosity, and1,4-phenylene for increasing the optical anisotropy. With regard to aconfiguration of 1,4-cyclohexylene, trans is preferred to cis forincreasing the maximum temperature.

Z¹, Z² and Z³ are independently a single bond, ethylene, methyleneoxy orcarbonyloxy, two of arbitrary Z¹ when k is 2 or 3 may be identical ordifferent, and two of arbitrary Z² when m is 2 or 3 may be identical ordifferent. Moreover, two of arbitrary Z³ when n is 2 or 3 may beidentical or different. Preferred Z¹ or Z² is a single bond fordecreasing the viscosity. Preferred Z³ is methyleneoxy for increasingthe absolute value of the dielectric anisotropy.

X¹ and X² are independently fluorine or chlorine. Preferred X¹ or X² isfluorine for increasing the dielectric anisotropy.

Y¹ is hydrogen or —CH₃. Preferred Y¹ is hydrogen for decreasing theviscosity.

Then, k, m and n are independently 1, 2 or 3. Preferred k is 2 or 3 forincreasing the maximum temperature, and 1 for decreasing the viscosity.Preferred m is 1 for decreasing the minimum temperature or decreasingthe viscosity, and 2 or 3 for increasing the maximum temperature.Preferred n is 2 for increasing the maximum temperature.

Fifth, the specific examples of the component compounds will be shown.In the preferred compounds described below, R⁷ is alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogenis replaced by fluorine; R¹⁰ is alkyl having 1 to 12 carbons, R¹¹ andR¹² are independently alkyl having 1 to 12 carbons, alkoxy having 1 to12 carbons or alkenyl having 2 to 12 carbons, and R¹³ and R¹⁴ areindependently alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons.

Preferred compound (1) includes compound (1-1-1) to compound (1-3-1).Further preferred compound (1) includes compound (1-1-1) and compound(1-2-1). Particularly preferred compound (1) includes compound (1-2-1).Preferred compound (2) includes compound (2-1-1) to compound (2-15-1).Further preferred compound (2) includes compound (2-1-1), compound(2-2-1), compound (2-4-1), compound (2-7-1) and compound (2-11-1).Particularly preferred compound (2) includes compound (2-1-1), compound(2-2-1), compound (2-4-1) and compound (2-7-1). Preferred compound (3)includes compound (3-1-1) to compound (3-13-1). Further preferredcompound (3) includes compound (3-1-1), compound (3-5-1), compound(3-7-1), compound (3-8-1) and compound (3-13-1). Particularly preferredcompound (3) includes compound (3-1-1) and compound (3-5-1). Preferredcompound (4) includes compound (4-1-1) to compound (4-5-1). Furtherpreferred compound (4) includes compound (4-2-1) and compound (4-4-1).

Sixth, the additive that may be mixed with the composition will beexplained. Such an additive includes the optically active compound otherthan the first component and the fifth component, the antioxidant, theultraviolet light absorber, the coloring matter, the antifoaming agent,the polymerizable compound and the polymerization initiator. Examples ofthe optically active compounds include compound (5-1) to compound (5-3).A preferred ratio of the optically active compound is about 5% by weightor less. A further preferred ratio is in the range of about 0.01% byweight to about 2% by weight.

When adding the optically active compound other than the first componentand the fifth component, an optically active compound having a twistdirection identical with a twist direction of the first component andthe fifth component, namely, compound (1) and compound (5), is preferredfor shortening a helical pitch of the composition. However, thecompounds having an identical twist direction and the compounds having areverse twist direction can be combined for adjusting temperaturedependency of length of the helical pitch of the composition.

The antioxidant is mixed with the composition for the purpose ofpreventing a decrease in specific resistance caused by heating in air,or maintaining a large voltage holding ratio at room temperature andalso at a temperature close to the maximum temperature of the nematicphase after the device has been used for a long time.

Preferred examples of the antioxidant include compound (6) where n is aninteger from 1 to 9. In compound (6), preferred n is 1, 3, 5, 7 or 9.Further preferred n is 1 or 7. Compound (6) where n is 1 is effective inpreventing a decrease in specific resistance caused by heating in airbecause the compound (6) has a large volatility. Compound (6) where n is7 is effective in maintaining a large voltage holding ratio at roomtemperature and also at a temperature close to the maximum temperatureof the nematic phase after the device has been used for a long timebecause the compound (6) has a small volatility. A preferred ratio ofthe antioxidant is about 50 ppm or more for achieving the effectthereof, and about 600 ppm or less for avoiding a decrease in maximumtemperature or avoiding an increase in minimum temperature. A furtherpreferred ratio is in the range of about 100 ppm to about 300 ppm.

Preferred examples of the ultraviolet light absorber include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also preferred. A preferred ratio of the ultraviolet light absorbersor the stabilizers is about 50 ppm or more for achieving the effectthereof, and about 10,000 ppm or less for avoiding a decrease in maximumtemperature or avoiding an increase in minimum temperature. A furtherpreferred ratio is in the range of about 100 ppm to about 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition to be adapted for a device having a guest host (GH)mode. A preferred ratio of the dye is in the range of about 0.01% byweight to about 10% by weight. The antifoaming agent such as dimethylsilicone oil or methyl phenyl silicone oil is mixed with the compositionfor preventing foam formation. A preferred ratio of the antifoamingagent is about 1 ppm or more for achieving the effect thereof, and about1,000 ppm or less for avoiding a poor display. A further preferred ratiois in the range of about 1 ppm to about 500 ppm.

The polymerizable compound is mixed with the composition to be adaptedfor the device having the polymer sustained alignment (PSA) mode.Preferred examples of the polymerizable compound include a compoundhaving a polymerizable group, such as acrylate, methacrylate, a vinylcompound, a vinyloxy compound, propenyl ether, an epoxy compound(oxirane, oxetane) and vinyl ketone. Particularly preferred examplesinclude an acrylate derivative or a methacrylate derivative. A preferredratio of the polymerizable compound is about 0.05% by weight or more forachieving the effect thereof, and about 10% by weight or less foravoiding a poor display. A further preferred ratio is in the range ofabout 0.1% by weight to about 2% by weight. The polymerizable compoundis preferably polymerized by irradiation with ultraviolet light or thelike in the presence of a suitable initiator such as aphotopolymerization initiator. Suitable conditions for polymerization,suitable types of the initiator and suitable amounts thereof are knownto a person skilled in the art and are described in literatures. Forexample, Irgacure 651 (registered trademark), Irgacure 184 (registeredtrademark) or Darocure 1173 (registered trademark) (Ciba Japan K.K.),each being a photoinitiator, is suitable for radical polymerization. Apreferred ratio of the photopolymerization initiator is in the range ofabout 0.1% by weight to about 5% by weight of the polymerizablecompound, and a particularly preferred ratio is in the range of about 1%by weight to about 3% by weight.

Seventh, the methods for synthesizing the component compounds will beexplained. The compounds can be prepared according to known methods.Examples of synthetic methods are shown. Compound (1-1-1) is prepared bythe method described in JP H6-200251 A (1994). Compound (2-1-1) isprepared by the method described in JP 2000-053602 A (2000). Compound(3-5-1) is prepared by the method described in JP S57-165328 A (1982).Compound (4) is prepared by the method described in JP 2005-35986 A(2005). The antioxidant is commercially available. A compoundrepresented by formula (6) where n is 1 is available from Sigma-AldrichCorporation. Compound (6) where n is 7 and so forth are preparedaccording to the method described in U.S. Pat. No. 3,660,505 B.

Any compounds whose synthetic methods are not described above can beprepared according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press) and NewExperimental Chemistry Course (Shin Jikken Kagaku Koza in Japanese)(Maruzen Co., Ltd.). The composition is prepared according to publiclyknown methods using the thus obtained compounds. For example, thecomponent compounds are mixed and dissolved in each other by heating.

Last, the application of the composition will be explained. Thecomposition of the invention mainly has a minimum temperature of about−10° C. or lower, a maximum temperature of about 70° C. or higher, andan optical anisotropy in the range of about 0.07 to about 0.20. Thedevice containing the composition has a large voltage holding ratio. Thecomposition is suitable for use in the AM device. The composition isparticularly suitable for use in a transmissive AM device. Thecomposition having an optical anisotropy in the range of about 0.08 toabout 0.25, and also the composition having an optical anisotropy in therange of about 0.10 to about 0.30 may be prepared by controlling theratio of the component compounds or by mixing with any other liquidcrystal compound. The composition can be used as the optically activecomposition because the composition contains the optically activecompound.

The composition can be used for the AM device, and also for a PM device.The composition can also be used for an AM device and a PM device havinga mode such as PC, TN, STN, ECB, OCB, IPS, VA or PSA. Use for the AMdevice having the TN, OCB or IPS mode is particularly preferred. Thedevice may be of a reflective type, a transmissive type or atransreflective type. Use for the transmissive device is preferred. Thecomposition can also be used for an amorphous silicon-TFT device or apolycrystal silicon-TFT device. The composition can also be used for anematic curvilinear aligned phase (NCAP) device prepared bymicroencapsulating the composition, and for a polymer dispersed (PD)device in which a three-dimensional network-polymer is formed in thecomposition.

EXAMPLES

In order to evaluate characteristics of a composition and a compound tobe contained in the composition, the composition and the compound weremade a measurement object. When the measurement object was thecomposition, the measurement object was measured as is, and valuesobtained were described. When the measurement object was the compound, asample for measurement was prepared by mixing the compound (15% byweight) into mother liquid crystals (85% by weight). Values ofcharacteristics of the compound were calculated according to anextrapolation method using values obtained by measurement:(extrapolated value)={(measured value of a sample formeasurement)−0.85×(measured value of mother liquid crystals)}/0.15.When a smectic phase (or crystals) precipitated at the ratio thereof at25° C., a ratio of the compound to the mother liquid crystals waschanged step by step in the order of (10% by weight:90% by weight), (5%by weight:95% by weight) and (1% by weight:99% by weight). Values of amaximum temperature, an optical anisotropy, viscosity and a dielectricanisotropy with regard to the compound were obtained according to theextrapolation method.

Components of the mother liquid crystals and the ratio thereof were asdescribed below.

Characteristics were measured according to the methods described below.Most of the methods are applied as described in EIAJ ED-2521A of theStandard of Electronic Industries Association of Japan, or as modifiedthereon.

Among measured values, as for values obtained using a liquid crystalcompound itself as the measurement object, and values obtained using aliquid crystal composition itself as the measurement object, unprocessedvalues were described as experimental data. When values were obtainedusing a sample for measurement obtained by mixing the compound into themother liquid crystals, values obtained by the extrapolation method weredescribed as the values of characteristics.

Twist Direction of Helix:

A helical pitch (P₁) of a composition in which 1 part by weight ofmeasurement object (optically active compound) was added to 100 parts byweight of the mother liquid crystals as previously described wasmeasured. Next, an adding amount of a standard optically active compoundwhere a helical pitch of a composition in which the standard opticallyactive compound was added to the identical mother liquid crystals becamecomparable to P₁ was calculated, and then a helical pitch (P₂) of acomposition in which a calculated amount of the standard opticallyactive compound was added to the other liquid crystals was measured.Furthermore, a helical pitch (P_(mix)) of a mixture in which identicalamounts of the compositions were mixed was measured. When P_(mix) was inthe middle between P₁ and P₂, the twist direction was judged to be aright-handed twist, and when P_(mix) clearly became larger than P₁ andP₂, the twist direction was judged to be a left-handed twist.

The standard optically active compound was as described below.

Maximum Temperature of a Nematic Phase (NI; ° C.):

A sample was placed on a hot plate in a melting point apparatus equippedwith a polarizing microscope and was heated at a rate of 1° C. perminute. Temperature when a part of the sample began to change from anematic phase to an isotropic liquid was measured. A higher limit of atemperature range of the nematic phase may be abbreviated as “maximumtemperature.”

Minimum Temperature of a Nematic Phase (T_(c); ° C.):

A sample having a nematic phase was put in glass vials and kept infreezers at temperatures of 0° C., −10° C., −20° C., −30° C. and −40° C.for 10 days, and then liquid crystal phases were observed. For example,when the sample maintained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., T_(c) was expressed asT_(c)≦−20° C. A lower limit of a temperature range of the nematic phasemay be abbreviated as “minimum temperature.”

Viscosity (bulk viscosity; measured at 20° C.; mPa·s):

A cone-plate (E type) viscometer was used for measurement.

Optical Anisotropy (refractive index anisotropy; Δn; measured at 25°C.):

Measurement was carried out by means of an Abbe refractometer with apolarizing plate mounted on an ocular, using light at a wavelength of589 nanometers. A surface of a main prism was rubbed in one direction,and then a sample was added dropwise onto the main prism. A refractiveindex (n∥) was measured when the direction of polarized light wasparallel to the direction of rubbing. A refractive index (n⊥) wasmeasured when the direction of polarized light was perpendicular to thedirection of rubbing. A value of optical anisotropy was calculated froman equation:Δn=n∥−n⊥.

Dielectric Anisotropy (Δc; measured at 25° C.):

A value of dielectric anisotropy was calculated from an equation:Δ∈=∈∥−∈⊥.A dielectric constant (∈∥ and ∈⊥) was measured as described below.1) Measurement of dielectric constant (∈∥): An ethanol (20 mL) solutionof octadecyl triethoxysilane (0.16 mL) was applied to a well-washedglass substrate. After rotating the glass substrate with a spinner, theglass substrate was heated at 150° C. for 1 hour. A sample was put in aVA device in which a distance (cell gap) between two glass substrateswas 4 micrometers, and the device was sealed with an ultraviolet-curableadhesive. Sine waves (0.5 V, 1 kHz) were applied to the device, andafter 2 seconds, a dielectric constant (∈∥) in the major axis directionof liquid crystal molecules was measured.2) Measurement of dielectric constant (∈⊥): A polyimide solution wasapplied to a well-washed glass substrate. After calcining the glasssubstrate, rubbing treatment was applied to the alignment film obtained.A sample was put in a TN device in which a distance (cell gap) betweentwo glass substrates was 9 micrometers and a twist angle was 80 degrees.Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2seconds a dielectric constant (∈⊥) in the minor axis direction of theliquid crystal molecules was measured.

Threshold Voltage (Vth; measured at 25° C.; V):

An LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. wasused for measurement. A light source was a halogen lamp. A sample wasput in a VA device having a normally black mode, in which a distance(cell gap) between two glass substrates was 4 micrometers and a rubbingdirection was anti-parallel, and the device was sealed with anultraviolet-curable adhesive. Voltage (60 Hz, rectangular waves) to beapplied to the device was stepwise increased from 0 V to 20 V at anincrement of 0.02 V. On the occasion, the device was irradiated withlight from a direction perpendicular to the device, and the amount oflight passing through the device was measured. A voltage-transmittancecurve was prepared, in which the maximum amount of light corresponds to100% transmittance and the minimum amount of light corresponds to 0%transmittance. A threshold voltage is voltage at 10% transmittance.

Voltage Holding Ratio (VHR-1; at 25° C.; %):

A TN device used for measurement had a polyimide alignment film, and adistance (cell gap) between two glass substrates was 5 micrometers. Asample was put in the device, and then the device was sealed with anultraviolet-curable adhesive. A pulse voltage (60 microseconds at 5 V)was applied to the TN device and the device was charged. A decayingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and area A between a voltage curve and a horizontal axis in a unit cyclewas obtained. Area B is an area without decay. A voltage holding ratiois a percentage of area A to area B.

Voltage Holding Ratio (VHR-2; at 80° C.; %):

A TN device used for measurement had a polyimide alignment film, and adistance (cell gap) between two glass substrates was 5 micrometers. Asample was put in the device, and then the device was sealed with anultraviolet-curable adhesive. A pulse voltage (60 microseconds at 5 V)was applied to the TN device and the device was charged. A decayingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and area A between a voltage curve and a horizontal axis in a unit cyclewas obtained. Area B is an area without decay. A voltage holding ratiois a percentage of area A to area B.

Voltage Holding Ratio (VHR-3; at 25° C.; %):

Stability to ultraviolet light was evaluated by measuring a voltageholding ratio after a device was irradiated with ultraviolet light. A TNdevice used for measurement had a polyimide alignment film and a cellgap was 5 micrometers. A sample was injected into the device, and thenthe device was irradiated with light for 20 minutes. A light source wasan ultra high-pressure mercury lamp USH-500D (made by Ushio, Inc.), anda distance between the device and the light source was 20 centimeters.In measuring VHR-3, a decaying voltage was measured for 16.7milliseconds. A composition having a large VHR-3 has a high stability toultraviolet light. A value of VHR-3 is preferably in the range of 90% ormore, further preferably, 95% or more.

Voltage Holding Ratio (VHR-4; at 25° C.; %):

A TN device into which a sample was injected was heated in aconstant-temperature bath at 80° C. for 500 hours, and then stability toheat was evaluated by measuring a voltage holding ratio. In measuringVHR-4, a decaying voltage was measured for 16.7 milliseconds. Acomposition having a large VHR-4 has a high stability to heat.

Response Time (τ; measured at 25° C.; ms):

An LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. wasused for measurement. A light source was a halogen lamp. A low-passfilter was set at 5 kHz. A sample was put in a VA device having anormally black mode, in which a distance (cell gap) between two glasssubstrates was 4 micrometers and a rubbing direction was anti-parallel,and the device was sealed with an ultraviolet-curable adhesive.Rectangular waves (60 Hz, 10 V, 0.5 second) were applied to the device.On the occasion, the device was irradiated with light from a directionperpendicular to the device, and the amount of light passing through thedevice was measured. The maximum amount of light corresponds to 100%transmittance, and the minimum amount of light corresponds to 0%transmittance. A response time is time required for a change from 90%transmittance to 10% transmittance (fall time; millisecond).

Specific Resistance (ρ; measured at 25° C.; Ωcm):

Into a vessel equipped with an electrode, 1.0 milliliter of a sample wasinjected. A DC voltage (10 V) was applied to the vessel, and a DCcurrent after 10 seconds was measured. A specific resistance wascalculated from the following equation:(specific resistance)={(voltage)×(electric capacity of vessel)}/{(DCcurrent)×(dielectric constant of vacuum)}.

Helical Pitch (P; measured at room temperature; μm):

A helical pitch was measured according to a wedge method (Handbook ofLiquid Crystals (Ekisho Binran in Japanese), page 196, (issued in 2000,Maruzen Co., Ltd.)). A sample was injected into a wedge cell and left tostand at room temperature for 2 hours, and then a gap (d2−d1) betweendisclination lines was observed by means of a polarizing microscope(Nikon Corporation, trade name. MM40/60 series). A helical pitch (P) wascalculated according to the following equation in which an angle of thewedge cell was expressed as θ:P=2×(d2−d1)×tan θ.

Gas Chromatographic Analysis:

GC-14B gas chromatograph made by Shimadzu Corporation was used formeasurement. A carrier gas was helium (2 mL per minute). A sampleinjector and a detector (FID) were set to 280° C. and 300° C.,respectively. A capillary column DB-1 (length 30 m, bore 0.32 mm, filmthickness 0.25 μm; dimethylpolysiloxane as a stationary phase,non-polar) made by Agilent Technologies, Inc. was used for separation ofcomponent compounds. After the column was kept at 200° C. for 2 minutes,the column was heated to 280° C. at a rate of 5° C. per minute. A samplewas prepared in an acetone solution (0.1% by weight), and then 1microliter of the solution was injected into the sample injector. Arecorder was C-R5A Chromatopac made by Shimadzu Corporation or theequivalent thereof. The resulting gas chromatogram showed a retentiontime of a peak and a peak area corresponding to each of the componentcompounds.

As a solvent for diluting a sample, chloroform, hexane and so forth mayalso be used. The following capillary columns may also be used forseparating component compounds: HP-1 (length 30 m, bore 0.32 mm, filmthickness 0.25 μm) made by Agilent Technologies, Inc., Rtx-1 (length 30m, bore 0.32 mm, film thickness 0.25 μm) made by Restek Corporation andBP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by SGEInternational Pty. Ltd. A capillary column CBP1-M50-025 (length 50 m,bore 0.25 mm, film thickness 0.25 μm) made by Shimadzu Corporation mayalso be used for the purpose of avoiding an overlap of peaks of thecompounds.

A ratio of liquid crystal compounds included in a composition may becalculated by the method as described below. The liquid crystalcompounds can be detected by means of a gas chromatograph. A ratio ofpeak areas in a gas chromatogram corresponds to a ratio (in the numberof moles) of the liquid crystal compounds. When the capillary columnsdescribed above were used, a correction coefficient of each of theliquid crystal compounds may be regarded as 1 (one). Accordingly, aratio (% by weight) of the liquid crystal compounds was calculated fromthe ratio of the peak areas.

The invention will be explained in detail by way of Examples. Theinvention is not limited by the Examples described below. The compoundsdescribed in Comparative Examples and Examples were expressed usingsymbols according to definitions in Table 3 below. In Table 3, aconfiguration of 1,4-cyclohexylene is trans. A parenthesized number nextto a symbolized compound in Examples corresponds to the number of thecompound. A symbol (−) means any other liquid crystal compound. A ratio(percentage) of liquid crystal compounds means weight percent (% byweight) based on the total weight of the liquid crystal compositionexcluding the first composition and the fifth composition. The liquidcrystal composition further includes an impurity in addition thereto.Last, values of characteristics of the composition were summarized.

TABLE 3 Method for Description of Compounds using Symbols R—(A₁)—Z₁— . .. —Z_(n)—(A_(n))—R′ 1) Left-terminal Group R— Symbol C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn— CH₂═CH— V—C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn—C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn— CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn— 2) Right-terminal Group —R′ Symbol —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn—C_(n)H_(2n)—CH═CH₂ —nV —CH═CF₂ —VFF —COOCH₃ —EMe 3) Bonding Group—Z_(n)— Symbol —C₂H₄— 2 —COO— E —CH═CH— V —C≡C— T —CF₂O— X —CH₂O— 10 4)Ring Structure —A_(n)— Symbol

H

Dh

dh

B

B(F)

B(2F)

B(2F,5F)

B(2F,3F)

B(2F,3F,6Me)

B(2F,3CL)

Cro(7F,8F) 5) Examples of Description Example 1 1V2-HH-3  

Example 2 3-HB(2F,3F)—O2  

Example 3 3-HHB-1  

Example 4 3-HDhB(2F,3F)—O4  

Comparative Example 1

V-HB(2F,3F)-O2 (2-1-1) 15%  V-HB(2F,3F)-O4 (2-1-1) 10%  3-HBB(2F,3F)-O2(2-7-1) 10%  5-HBB(2F,3F)-O2 (2-7-1) 10%  2-HHB(2F,3CL)-O2 (2-8-1) 3%3-HHB(2F,3CL)-O2 (2-8-1) 3% 5-HHB(2F,3CL)-O2 (2-8-1) 3% 2-HH-3 (3-1-1)26%  3-HH-4 (3-1-1) 4% 3-HHB-1 (3-5-1) 4% 3-HHB-O1 (3-5-1) 3% 3-HHEBH-3(3-10-1) 5% 5-HBB(3F)B-2 (3-13-1) 4%

Into 100 parts by weight of the composition, 1 part by weight of thefollowing compound (left-handed twist) that is different from a firstcomponent of the invention was added.

NI=86.6° C.; Tc≦−20° C.; Δn=0.093; Δ∈=−2.8; η=21.6 mPa·s; P=117.3 μm.

Example 1

V-HB(2F,3F)-O2 (2-1-1) 15%  V-HB(2F,3F)-O4 (2-1-1) 10%  3-HBB(2F,3F)-O2(2-7-1) 10%  5-HBB(2F,3F)-O2 (2-7-1) 10%  2-HHB(2F,3CL)-O2 (2-8-1) 3%3-HHB(2F,3CL)-O2 (2-8-1) 3% 5-HHB(2F,3CL)-O2 (2-8-1) 3% 2-HH-3 (3-1-1)26%  3-HH-4 (3-1-1) 4% 3-HHB-1 (3-5-1) 4% 3-HHB-O1 (3-5-1) 3% 3-HHEBH-3(3-10-1) 5% 5-HBB(3F)B-2 (3-13-1) 4%

Into 100 parts by weight of the composition, 1 part by weight of thefollowing compound (1-1-1; left-handed twist) was added.

NI=86.5° C.; Tc≦−20° C.; Δn=0.093; Δ∈=−2.8; η=21.8 mPa·s; P=19.4 μm.

Example 2

3-H2B(2F,3F)-O2 (2-2-1) 17%  5-H2B(2F,3F)-O2 (2-2-1) 17% 2-HHB(2F,3CL)-O2 (2-8-1) 3% 3-HHB(2F,3CL)-O2 (2-8-1) 4% 3-HBB(2F,3CL)-O2(2-9-1) 6% 5-HBB(2F,3CL)-O2 (2-9-1) 6% 3-HH-V (3-1-1) 22%  V-HHB-1(3-5-1) 7% 2-BB(3F)B-3 (3-7-1) 8% 3-HHEBH-3 (3-10-1) 5% 3-HHEBH-4(3-10-1) 5%

Into 100 parts by weight of the composition, 1 part by weight of thefollowing compound (1-2-1; left-handed twist) was added.

NI=87.0° C.; Tc≦−30° C.; Δn=0.101; Δ∈=−2.4; η=22.8 mPa·s; P=18.1 μm.

Example 3

V-HB(2F,3F)-O2 (2-1-1) 10%  V-HB(2F,3F)-O4 (2-1-1) 6% 3-H1OB(2F,3F)-O2(2-3-1) 5% V-HHB(2F,3F)-O2 (2-4-1) 8% V-HHB(2F,3F)-O4 (2-4-1) 5%3-HBB(2F,3F)-O2 (2-7-1) 11%  5-HBB(2F,3CL)-O2 (2-9-1) 5% 3-HH-V (3-1-1)30%  3-HHEH-3 (3-4-1) 4% V2-HHB-1 (3-5-1) 6% 5-HBBH-3 (3-11-1) 5%3-HH1OCro(7F,8F)-5 (4-4-1) 5%

Into 100 parts by weight of the composition, 1 part by weight of thefollowing compound (1-3-1; left-handed twist) was added.

NI=86.9° C.; Tc≦−20° C.; Δn=0.091; Δ∈=−2.7; η=23.8 mPa·s; P=19.5

Example 4

3-HB(2F,3F)-O2 (2-1-1) 10%  3-H2B(2F,3F)-O2 (2-2-1) 13%  V-HHB(2F,3F)-O2(2-4-1) 5% V-HHB(2F,3F)-O4 (2-4-1) 5% 3-HH1OB(2F,3F)-O2 (2-6-1) 4%5-HH1OB(2F,3F)-O2 (2-6-1) 3% V-HBB(2F,3F)-O2 (2-7-1) 10% 5-HDhB(2F,3F)-O2 (2-11-1) 10%  2-HH-3 (3-1-1) 7% 4-HH-V (3-1-1) 6%5-HH-V (3-1-1) 16%  3-HHB-O1 (3-5-1) 3% 3-HHEBH-3 (3-10-1) 4%5-HBB(3F)B-2 (3-13-1) 4%

Into 100 parts by weight of the composition, 0.5 part by weight of thefollowing compound (1-2-1; left-handed twist) was added.

NI=92.0° C.; Tc≦−20° C.; Δn=0.093; Δ∈=−3.2; η=23.8 mPa·s; P=33.6 μm.

Example 5

3-HB(2F,3F)-O2 (2-1-1) 5% V-HB(2F,3F)-O2 (2-1-1) 9% 3-HHB(2F,3F)-1(2-4-1) 10%  3-HH2B(2F,3F)-O2 (2-5-1) 10%  5-HBB(2F,3CL)-O2 (2-9-1) 3%V-DhHB(2F,3F)-O2 (2-10-1) 3% 3-HH-V (3-1-1) 19%  3-HH-VFF (3-1-1) 4%5-HB-O2 (3-2-1) 6% 1V-HBB-2 (3-6-1) 5% 1-BB(3F)B-2V (3-7-1) 6%2-BBB(2F)-3 (3-8-1) 7% 3-HH1OH-3 (3) 3% 3-H1OCro(7F,8F)-5 (4-2-1) 3%2-HH1OCro(7F,8F)-5 (4-4-1) 3% 3-HH1OCro(7F,8F)-5 (4-4-1) 4%

Into 100 parts by weight of the composition, 0.8 part by weight of thefollowing compound (1-1-1; left-handed twist) was added.

NI=83.2° C.; Tc≦−30° C.; Δn=0.107; Δ∈=−2.3; η=23.1 mPa·s; P=23.0 μm.

Example 6

1V2-HB(2F,3F)-O2 (2-1-1) 10%  3-H2B(2F,3F)-O2 (2-2-1) 10% 1V2-HHB(2F,3F)-O2 (2-4-1) 5% 5-HH2B(2F,3F)-O2 (2-5-1) 8% 3-HBB(2F,3F)-O2(2-7-1) 10%  3-HHB(2F,3CL)-O2 (2-8-1) 4% 3-dhHB(2F,3F)-O2 (2-12-1) 3%3-HH1OB(2F,3F,6Me)-O2 (2-15-1) 5% 2-HH-3 (3-1-1) 20%  3-HH-O1 (3-1-1) 4%V2-BB-1 (3-3-1) 5% 3-HHB-3 (3-5-1) 3% 3-HB(3F)HH-5 (3-9-1) 5%5-HB(3F)HH-V (3-9-1) 3% 3-HH1OCro(7F,8F)-5 (4-4-1) 5%

Into 100 parts by weight of the composition, 0.7 part by weight of thefollowing compound (1-2-1; right-handed twist) was added.

NI=92.4° C.; Tc≦−20° C.; Δn=0.096; Δ∈=−3.1; η=23.7 mPa·s; P=24.7 μm.

Example 7

3-HB(2F,3F)-O2 (2-1-1) 10% 3-HB(2F,3F)-O4 (2-1-1) 10% 3-HHB(2F,3F)-O2(2-4-1) 10% 5-HHB(2F,3F)-O2 (2-4-1) 10% 3-dhBB(2F,3F)-O2 (2-13-1)  5%3-HH2B(2F,3F,6Me)-O2 (2-14-1)  5% 2-HH-3 (3-1-1) 25% 3-HH-V (3-1-1) 10%7-HB-1 (3-2-1)  5% 3-HBB(3F)B-4 (3-13-1)  5% 5-HBB(3F)B-2 (3-13-1)  5%

Into 100 parts by weight of the composition, 2 parts by weight of thefollowing compound (1; left-handed twist) was added.

NI=83.6° C.; Tc≦−20° C.; Δn=0.089; Δ∈=−2.3; η=197 mPa·s; VHR-1=99.6%;VHR-2=98.9%; VHR-3=98.9%; P=49.3 μm.

Example 8

3-HB(2F,3F)-O2 (2-1-1) 10%  V-HHB(2F,3F)-O2 (2-4-1) 5% 4-HBB(2F,3F)-O2(2-7-1) 10%  3-HDhB(2F,3F)-1 (2-11-1) 5% 2O-B(2F,3F)B(2F,3F)-O6 (2) 5%4O-B(2F,3F)B(2F,3F)-O6 (2) 5% 3-HH-V (3-1-1) 30%  3-HH-V1 (3-1-1) 7%V2-BB-1 (3-3-1) 5% 5-HB(3F)BH-3 (3-12-1) 5% 5-HBB(3F)B-2 (3-13-1) 5%5-HBB(3F)B-3 (3-13-1) 5% 2-BB(2F,3F)B-3 (—) 3%

Into 100 parts by weight of the composition, 0.3 part by weight of thefollowing compound (1-3-1; right-handed twist) was added.

NI=82.6° C.; Tc≦−20° C.; Δn=0.113; Δ∈=−2.2; η=20.9 mPa·s; P=63.0 μm.

Example 9

V-HB(2F,3F)-O2 (2-1-1) 15%  1V2-H2B(2F,3F)-O2 (2-2-1) 9% 3-HHB(2F,3F)-O2(2-4-1) 13%  2-HH-3 (3-1-1) 17%  4-HH-V (3-1-1) 6% 1V2-BB-1 (3-3-1) 4%3-HHB-1 (3-5-1) 3% V2-HHB-1 (3-5-1) 10%  2-BBB(2F)-3 (3-8-1) 5%3-H1OCro(7F,8F)-5 (4-2-1) 3% 3-HH1OCro(7F,8F)-5 (4-4-1) 5%5-HH1OCro(7F,8F)-3 (4-4-1) 5% 1O1-HBBH-4 (—) 5%

Into 100 parts by weight of the composition, 0.3 part by weight of thefollowing compound (1-2-1; left-handed twist) was added.

NI=82.3° C.; Tc≦−20° C.; Δn=0.095; Δ∈=−2.6; η=22.7 mPa·s; VHR-1=99.4%;VHR-2=98.5%; P=59.5 μm.

Example 10

3-HB(2F,3F)-O2 (2-1-1) 8% 3-HB(2F,3F)-O4 (2-1-1) 9% 3-H1OB(2F,3F)-O2(2-3-1) 5% 3-HBB(2F,3F)-O2 (2-7-1) 12%  5-HBB(2F,3F)-O2 (2-7-1) 11% 3-DhHB(2F,3F)-O2 (2-10-1) 5% 4O-B(2F,3F)B(2F,3F)-O6 (2) 3% 2-HH-3(3-1-1) 6% 3-HH-V (3-1-1) 24%  3-HHB-1 (3-5-1) 3% 3-HHEBH-3 (3-10-1) 3%3-HHEBH-4 (3-10-1) 3% 5-H1OCro(7F,8F)-5 (4-2-1) 3% 3-HH1OCro(7F,8F)-5(4-4-1) 5%

Into 100 parts by weight of the composition, 0.3 part by weight of thefollowing compound (1-1-1; right-handed twist) was added.

NI=82.2° C.; Tc≦−20° C.; Δn=0.094; Δ∈=−3.6; η=24.9 mPa·s; VHR-1=99.5%;VHR-2=98.4%; P=61.5 μm.

Example 11

3-H2B(2F,3F)-O2 (2-2-1) 23%  5-H2B(2F,3F)-O2 (2-2-1) 22% 3-HBB(2F,3F)-O2 (2-7-1) 6% 4-HBB(2F,3F)-O2 (2-7-1) 6% 5-HBB(2F,3F)-O2(2-7-1) 6% 3-HHB(2F,3CL)-O2 (2-8-1) 6% 4-HHB(2F,3CL)-O2 (2-8-1) 5%5-HHB(2F,3CL)-O2 (2-8-1) 5% 2-HH-3 (3-1-1) 9% 3-HB-O2 (3-2-1) 4% 3-HHB-1(3-5-1) 4% 5-HBB(3F)B-2 (3-13-1) 4%

Into 100 parts by weight of the composition, 0.3 part by weight of thefollowing compound (1-1-1; left-handed twist) and 0.3 part by weight ofthe following compound (5; left-handed twist) was added.

NI=75.9° C.; Tc≦−20° C.; Δn=0.103; Δ∈=−4.5; η=33.6 mPa·s; P=28.0 μm.

Example 12

3-HB(2F,3F)-O2 (2-1-1) 13% V-HB(2F,3F)-O2 (2-1-1) 16% V-HB(2F,3F)-O4(2-1-1) 12% 3-HBB(2F,3F)-O2 (2-7-1) 10% 4-HBB(2F,3F)-O2 (2-7-1)  9%5-HBB(2F,3F)-O2 (2-7-1) 10% 3-HH-4 (3-1-1) 10% 3-HHB-1 (3-5-1)  4%3-HHB-O1 (3-5-1)  4% 3-HHB-3 (3-5-1)  6% 5-HBB(3F)B-2 (3-13-1)  6%

Into 100 parts by weight of the composition, 0.3 part by weight of thefollowing compound (1-2-1; left-handed twist) and 0.3 part by weight ofthe following compound (5; left-handed twist) was added.

NI=84.5° C.; Tc≦−20° C.; Δn=0.116; Δ∈=−4.1; η=27.5 mPa·s; P=26.8 μm.

Example 13

3-HB(2F,3F)-O2 (2-1-1) 14%  5-HB(2F,3F)-O2 (2-1-1) 14%  V-HB(2F,3F)-O4(2-1-1) 11%  3-HBB(2F,3F)-O2 (2-7-1) 12%  4-HBB(2F,3F)-O2 (2-7-1) 7%5-HBB(2F,3F)-O2 (2-7-1) 7% 3-HHB(2F,3CL)-O2 (2-8-1) 3% 4-HHB(2F,3CL)-O2(2-8-1) 4% 3-HH-4 (3-1-1) 3% 3-HB-O2 (3-2-1) 10%  3-HHB-1 (3-5-1) 4%3-HHB-O1 (3-5-1) 3% 3-HHB-3 (3-5-1) 3% 5-HBB(3F)B-2 (3-13-1) 5%

Into 100 parts by weight of the composition, 0.5 part by weight of thefollowing compound (1-2-1; left-handed twist) and 0.3 part by weight ofthe following compound (5; left-handed twist) was added.

NI=86.2° C.; Tc≦−20° C.; Δn=0.119; Δ∈=−4.2; η=30.7 mPa·s; P=20.4 μm.

Example 14

3-HB(2F,3F)-O2 (2-1-1) 14%  5-HB(2F,3F)-O2 (2-1-1) 14%  V-HB(2F,3F)-O4(2-1-1) 11%  3-HBB(2F,3F)-O2 (2-7-1) 12%  4-HBB(2F,3F)-O2 (2-7-1) 7%5-HBB(2F,3F)-O2 (2-7-1) 7% 3-HHB (2F,3CL)-O2 (2-8-1) 3% 4-HHB(2F,3CL)-O2(2-8-1) 4% 3-HH-4 (3-1-1) 3% 3-HB-O2 (3-2-1) 10%  3-HHB-1 (3-5-1) 4%3-HHB-O1 (3-5-1) 3% 2-BBB(2F)-5 (3-8-1) 3% 5-HBB(3F)B-2 (3-13-1) 5%

Into 100 parts by weight of the composition, 0.5 part by weight of thefollowing compound (1-2-1; left-handed twist) and 0.3 part by weight ofthe following compound (5; left-handed twist) was added.

NI=85.3° C.; Tc≦−20° C.; Δn=0.123; Δ∈=−4.1; η=30.9 mPa·s; P=20.8 μm.

The compositions according to Examples 1 to 14 have a shorter helicalpitch in comparison with the composition according to ComparativeExample 1. Thus, the liquid crystal composition according to theinvention is so much superior in characteristics to the compositionshown in Comparative Example 1.

INDUSTRIAL APPLICABILITY

The invention provides a liquid crystal composition satisfying at leastone of characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of the nematic phase, a smallviscosity, a large optical anisotropy, a large negative dielectricanisotropy, a large specific resistance, a high stability to ultravioletlight, a high stability to heat and a short helical pitch, or provides aliquid crystal composition having a suitable balance regarding at leasttwo of the characteristics. A liquid crystal display device using theliquid crystal composition is applied as an AM device having a shortresponse time, a large voltage holding ratio, a large contrast ratio, along service life, a small light leakage and so forth, and thus can besuitably used for an AM device and so forth.

What is claimed is:
 1. A liquid crystal composition that has a negativedielectric anisotropy and contains at least one optically activecompound selected from the group of compounds represented by formula (1)as a first component and at least one compound selected from the groupof compounds represented by formula (2) as a second component:

wherein R¹, R⁴ and R⁵ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; R² and R³ are each differently alkyl having 1 to 12 carbonsor alkenyl having 2 to 12 carbons; ring A and ring B are independently1,4-cyclohexylene or 1,4-phenylene; ring C is independently1,4-cyclohexylene, 1,4-phenylene in which arbitrary hydrogen may bereplaced by fluorine or chlorine, or tetrahydropyran-2,5-diyl; Z¹ isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; X¹and X² are independently fluorine or chlorine; Y¹ is hydrogen or —CH₃;and k is 1, 2 or
 3. 2. The liquid crystal composition according to claim1, wherein, in formula (1), a sum of carbons of R² and R³ is in therange of 3 to
 10. 3. The liquid crystal composition according to claim1, wherein the first component is at least one compound selected fromthe group of compounds represented by formula (1-1) to formula (1-3):

wherein R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine.
 4. Theliquid crystal composition according to claim 1, wherein the secondcomponent is at least one compound selected from the group of compoundsrepresented by formula (2-1) to formula (2-15):

wherein R⁴ and R⁵ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 5. The liquid crystal composition according to claim 1,further containing at least one compound selected from the group ofcompounds represented by formula (3) as a third component:

wherein R⁶ and R⁷ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring D and ring E are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z² isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andm is 1, 2 or
 3. 6. The liquid crystal composition according to claim 5,wherein the third component is at least one compound selected from thegroup of compounds represented by formula (3-1) to formula (3-13):

wherein R⁶ and R⁷ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 7. The liquid crystal composition according to claim 1,further containing at least one compound selected from the group ofcompounds represented by formula (4) as a fourth component:

wherein R⁸ and R⁹ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring F is independently 1,4-cyclohexylene, 1,4-phenylene inwhich arbitrary hydrogen may be replaced by fluorine or chlorine, ortetrahydropyran-2,5-diyl; Z³ is independently a single bond, ethylene,methyleneoxy or carbonyloxy; and n is 1, 2 or
 3. 8. The liquid crystalcomposition according to claim 7, wherein the fourth component is atleast one compound selected from the group of compounds represented byformula (4-1) to formula (4-5):

wherein R⁸ and R⁹ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 9. The liquid crystal composition according to claim 1,further containing a compound represented by formula (5) as a fifthcomponent:


10. The liquid crystal composition according to claim 1, wherein a ratioof the first component is in the range of 0.01 part by weight to 5 partsby weight based on 100 parts by weight of the liquid crystal compositionexcluding the first component and the fifth component.
 11. The liquidcrystal composition according to claim 1, wherein a ratio of the secondcomponent is in the range of 5% by weight to 80% by weight based on theweight of the liquid crystal composition excluding the first componentand the fifth component.
 12. The liquid crystal composition according toclaim 5, wherein a ratio of the third component is in the range of 5% byweight to 80% by weight based on the weight of the liquid crystalcomposition excluding the first component and the fifth component. 13.The liquid crystal composition according to claim 7, wherein a ratio ofthe fourth component is in the range of 3% by weight to 30% by weightbased on the weight of the liquid crystal composition excluding thefirst component and the fifth component.
 14. The liquid crystalcomposition according to claim 1, wherein a maximum temperature of anematic phase is 70° C. or higher, an optical anisotropy (25° C.) at awavelength of 589 nanometers is 0.08 or more, and a dielectricanisotropy (25° C.) at a frequency of 1 kHz is −2 or less.
 15. A liquidcrystal display device, containing the liquid crystal compositionaccording to claim
 1. 16. The liquid crystal display device according toclaim 15, wherein an operating mode in the liquid crystal display deviceis a VA mode, an IPS mode or a PSA mode, and a driving mode in theliquid crystal display device is an active matrix mode.
 17. The liquidcrystal composition according to claim 5, further containing at leastone compound selected from the group of compounds represented by formula(4) as a fourth component:

wherein R⁸ and R⁹ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring F is independently 1,4-cyclohexylene, 1,4-phenylene inwhich arbitrary hydrogen may be replaced by fluorine or chlorine, ortetrahydropyran-2,5-diyl; Z³ is independently a single bond, ethylene,methyleneoxy or carbonyloxy; and n is 1, 2 or
 3. 18. The liquid crystalcomposition according to claim 17, wherein the fourth component is atleast one compound selected from the group of compounds represented byformula (4-1) to formula (4-5):

wherein R⁸ and R⁹ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 19. The liquid crystal composition according to claim 17,wherein a ratio of the fourth component is in the range of 3% by weightto 30% by weight based on the weight of the liquid crystal compositionexcluding the first component and the fifth component.